Last week I made a fourth raised bed for the garden; like the previous 3, the wood came from a couple of deconstructed pallets rescued from a nearby skip. It took me just over an hour (with power tools: a hand-held circular saw and a drill with screwdriver fitting; add about another 30-60 min if using hand tools), which did not include the time to deconstruct the pallets. Here's how I went about it (apologies for the lack of as-you-go photos; I wasn't thinking of blogging it at the time!).
The basic construction is 3 pallet-planks per side (for a total of 12 needed), cut to the size needed (in my case, 3 paving slab widths on the long sides and 2 on the short, to fit the intended gap). Measure up your planks, and cut them to size.
The next step is to attach everything together. It's possible just to nail/screw the planks directly to one another at the corners, but that won't be very stable. A better bet is to use a thicker piece of wood as a brace at each corner, and screw the planks to that. Happily, pallets are constructed with a couple of nice thick ribs down their middles which are ideal for this. Cut 4 corner braces from this. The length of each brace should match the width of 3 planks, so that it's the same height as the plank-sides of your raised bed.
Take the first set of three long planks, and two of the corner braces, and screw the planks to the braces at each end. Repeat with the other set of long planks and the other two corner braces. You now have two long sides of a rectangle, each held together by the braces, but not attached to each other.
Now screw the two sets of three shorter planks into the braces at each end, to make the short sides of the rectangle.
From the outside, planks on two sides screwed to the brace. As a rule, the long and short sides should be the same height, but my planks were slightly different widths and that didn't quite work out. Aesthetically suboptimal but still perfectly functional!
That's it! These should be pretty sturdy, especially once filled with soil to strengthen them. You can rest them on existing soil (in my case, where I've levered up the paving slabs from the garden), or, if you make them slightly deeper, you can put them straight onto concrete, put cardboard at the bottom and shovel compost in at the top, and treat them as a very large container.
Note on tools and fixings:
- You can do all of this with a hand saw, and I have done in the past, but a hand-held circular saw makes it all a lot quicker (and in my case, at 7 months pregnant, makes it feasible; I'd have struggled to construct this on my own by hand).
- Nails can substitute for screws, but they won't be as secure.
- Whatever the packet may say, screws go in quicker and easier if you drill pilot holes first. The screwdriver fitting on a power drill is also a godsend, but again, hand tools do the job, just a little slower.
- A set-square is useful to get the cut lines straight. If you don't have a set square, all hand saws have a right-angle marker and a 45 degree marker on the handle.